1. Field of the Invention
The present invention is in the field of gas dynamics, and specifically relates to a device for thoroughly mixing one or more solute gases with a diluent gas so as to provide a blended mixture that is extremely homogeneous so that it can be used as a standard in certain applications in the semiconductor industry.
2. The Prior Art
In U.S. Pat. No. 3,799,195 issued Mar. 26, 1974, Hermans describes a device whose objective is to achieve a strictly constant ratio between two components of a gas mixture in spite of large variations in the flow rate. One of the gases flows axially into the large end of the converging chamber of a venturi, and the other gas is introduced transversely to the axis of the venturi at the region of maximum velocity. The gases become mixed as they flow through the expansion chamber of the venturi. The contracting chamber includes a nozzle at its smallest diameter portion, and the position of this nozzle relative to the expansion chamber is altered in a controlled manner to vary the mixture ratio.
In U.S. Pat. No. 2,493,387 issued Jan. 3, 1950, Campbell shows a flow mixer in which the diluent gas enters axially through a short compression chamber while the solute gas is introduced transversely to the axis of the venturi at the point of maximum velocity. Mixing occurs in an expansion chamber.
Japanese Patent No. 0099264 issued Aug. 4, 1979 shows a device for the simultaneous dilution of several kinds of liquid. The solutes are introduced transversely to the axis of a venturi at the point of maximum flow velocity.
The above patents have in common the technique of introducing the solute at the point of maximum velocity, which is also the point of least pressure or greatest suction. There may be reasons for this, but in any case, the present invention employs a different technique. Also, most prior art devices inject the solute in a direction transverse to the axis of the venturi, i.e., radially. The present invention employs a different approach.